The present invention generally relates to a system and/or a method for reading, measuring and/or controlling intensity of light emitted from a light-emitting diode (LED). More specifically, the present invention relates to a system and/or a method that may have a light detector located in a position adjacent to the LED for reading and/or measuring the intensity of light emitted from the LED. A cavity may house the LED and/or the light detector, and/or the cavity may have an aperture through which the LED may emit light.
It is generally known that an LED is a semiconductor diode that has a chip of semiconducting material doped with impurities to create a p-n junction. The semiconductor diode emits light when the same is electrically biased in a forward direction of the p-n junction. The emitted light may be, for example, infrared light, visible light and/or near ultraviolet light. Further, the color of the emitted light varies depending on the semiconducting material used. Additionally, optics are added to the chip to shape a radiation pattern of the emitted light.
Further, it is generally known that an intensity of the emitted light varies over time. The intensity of the emitted light may be controlled by varying a voltage and/or a current of electricity applied to the LED. Therefore, control systems are provided to measure intensity of emitted light and to control the voltage and/or the current applied to the LED to produce a more stable intensity of emitted light over time.
However, the LED is often used in open systems where the LED may be exposed to ambient light. The ambient light may be emitted from light sources external to the LED. The ambient light may be light emitted from the LED that has been reflected from a surface located adjacent to the LED. It is generally known that ambient light is absorbed and/or reflected by the LED and/or the semiconducting material. Absorption of the ambient light by the semiconducting material alters the properties of the semiconducting material and contributes to the varying intensity of emitted light. Moreover, ambient light is often passively detected by the control systems. Therefore, known control systems measure intensity of emitted light and, inadvertently, ambient light to control the voltage and/or the current applied to the LED. As a result, the intensity of light emitted from the LED used with known control systems varies substantially over time even when used in conjunction with known control systems designed to prevent the same.
A need, therefore, exists for a system and/or a method for reading, measuring and/or controlling intensity of light emitted from an LED. Additionally, a need exists for a system and/or a method that may prevent and/or may retard reflection of ambient light from a surface of the LED to allow an accurate reading and/or an accurate measurement of the intensity of light emitted from the LED. Further, a need exists for a system and/or a method that may prevent absorption of ambient light by a semiconducting material of the LED to control intensity of light emitted from the LED. Still further, a need exists for a light detector that may be exposed only to light emitted by the LED. Still further, a need exists for a control circuit that may be electrically connected to both the light detector and the LED for measuring and/or for controlling intensity of light emitted from the LED. Moreover, a need exists for a cavity that may surround the light detector to limit exposure of the light detector to ambient light.